Molecular cloning and expression of feline CD3ε

The cDNA of feline CD3 epsilon, one of the T-cell receptor components, was cloned from a feline T-lymphoblastoid cell line (MYA-1 cells) and peripheral blood, mononuclear cells and thymocytes of cats by polymerase chain reaction. Sequencing analysis revealed that the open reading frame of feline CD3 epsilon consists of 606 base pairs encoding a predicted molecular mass of 25 kDa transmembrane protein which lacks N-glycosylation site. Comparison of the predicted amino acid sequence of feline CD3 epsilon with those of other mammalians' homologues revealed that a relatively low homology was present in the extracellular domain. However, the cytoplasmic domain contained several characteristic motifs highly conserved across the species. These motifs were known to be important for signal transduction upon T-cell activation or endoplasmic reticulum retention. In addition, the feline CD3 epsilon protein was expressed in an insect cell line (Sf9) by a baculovirus expression system. The expression was confirmed by indirect immunofluorescence assay and immunoblotting analysis using an anti-human CD3 epsilon polyclonal antibody. These results will provide additional information for understanding the feline immune system. (C) 1998 Published by Elsevier Science B.V. All rights reserved.